Open AccessThree‐dimensional profiling of collimated radio‐frequency orbital angular momentum beams
Author(s) -
Hamilton Joshua K.,
Berry Simon J.,
Spencer Joseph H.,
Lawrence Christopher R.,
Smith Francis C.,
Drysdale Timothy D.
Publication year - 2020
Publication title -
iet microwaves, antennas and propagation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.555
H-Index - 69
eISSN - 1751-8733
pISSN - 1751-8725
DOI - 10.1049/iet-map.2019.0808
Subject(s) - collimated light , optics , angular momentum , physics , beam divergence , beam (structure) , antenna (radio) , beam diameter , laser beams , telecommunications , engineering , laser , quantum mechanics
The use of orbital angular momentum (OAM) modes in radio communication is thought to enhance capacity. This work focuses on using the l = +1 mode transmitted from a 180 mm diameter, 8‐element circular antenna array. The transmitted OAM beam was collimated by using a spherical mirror and the intensity and phase were investigated. A xyz scanning stage was used to profile the propagating OAM beam in three dimensions, resulting in a detailed investigation into the effects of collimation on the OAM beam. The proposed system was shown to reduce the beam divergence from 36.6° to 1.2°, without affecting the OAM mode purity of the beam for a frequency range of 4–6 GHz. This investigation showed a step towards realising practical control over the divergence of OAM‐carrying beams.